Motor vehicle cooling systems for cooling engine coolant, refrigerant vapor and transmission oil are known in which either an oil cooler or refrigerant condenser unit are located upstream from the cooling air inlet side of the radiator for heat from the coolant system for a liquid cooled engine. Such refrigerant condensers and oil coolers have separate air centers and the radiator has separate air centers.
In order to meet space and weight design constraints and inlet air stream flow patterns in a motor vehicle, a combined radiator and condenser apparatus has been utilized as disclosed in U.S. Pat. No. 5,009,262, issued Apr. 23, 1991 in the name of Halstead et al, and assigned to the assignee of the subject invention. The combination apparatus provides thin gauge aluminum centers which are common for both the radiator and condenser, and each of the radiator and condenser units share a common tank member and common header plates. An extruded tank has an integral internal partition which separates the extruded tank into a coolant chamber and a high pressure refrigerant chamber. The tube passes of both the radiator and the condenser are bonded to an integral wall of the extruded tank at tube access slots therein. The tubes have the same air centers for defining a single air flow pass through both the radiator and the condenser.
One concern associated with this design is the conduction of heat from coolant to refrigerant. The water/glycol solution flowing in the radiator tubes has a temperature in the range of 100.degree. F. higher than the freon flowing in the condenser tubes. This temperature difference will result in heat conduction from coolant to freon and will reduce the condenser performance significantly, which in turn will adversely affect the performance of the vehicle air conditioning system.